First of all visualize exactly how you want the deck to function. Depending on this plan how everything will fit together.
Deciding on which direction the deck building boards will run i.e. parallel to the house or perpendicular is important because both has its own advantages and disadvantages. However, it is always better to have the post at the edge since this gives the railing best support. Also it is better to have the deck not attached to the house as water may find its way in.
Next, dig holes at least two feet deep where the support post will be located. These posts can be placed in concrete instead of using bolts and hangers. Then attach the joist to the header joist using joist hangers or use nails through the header joist into the end of the joist. An important point to note at this stage of deck building process is that every joist is the correct length so that any trimming is not required during attachment at the other end. Attach the other end of the joist to have the basic frame in place and the post to hold the railings.

To place the stair stringer for the steps the stringers should be placed in a way to allow a 36 inches wide stair. Nail from the backside into the stringer or use joist hangers to support the stringers and support the bottom edge on concrete if possible. After the stringers are in place, place the steps one by one.

After this attach the deck boards to the floor joist starting at the outside and working toward the house. Before nailing them down look at the edge. The grain should run concave or down on the edges to prevent water logging. Finally place the railings one by one. Then take some long smooth deck boards and place on top of the post and the railings and nail into place.

The deck is useable now. You can install some skirting around the bottom of the deck to give them a great look.

this looks like a good start for a newbie like me.
Before I embark, I would appreciate it if you tell me a few more ideas about:
1. What are the set of Tools ( powered and otherwise) I will need through out this project?
2. what do we do to treat the lawn / grass under the deck? Am sure it'll grow wild in a few weeks
3. Can I plan it in 2 phases, one to do the deck and one to set up the roof?
4. Lastly, for a 14'X12' deck (approx) where can I get a design plan and a List of Materials to purchase and specify at Home Depot / Lowes to minimize my effort and expense.